Avoid unnecessary AtomString creation in bestFitSourceForImageAttributes callers

[cdumez]

3e936c5

Avoid unnecessary AtomString creation in bestFitSourceForImageAttributes callers
https://bugs.webkit.org/show_bug.cgi?id=312863

Reviewed by Darin Adler and Ryosuke Niwa.

bestFitSourceForImageAttributes() was taking `const AtomString&` for its
srcAttribute parameter, but only calls isNull(), isEmpty(), and passed it to
StringViewWithUnderlyingString — none of which require AtomString. Three of its
five callers constructed a temporary AtomString from a String just to satisfy the
signature, which hashes the string and inserts it into the global atom table for
no benefit.

Change the parameter type to `const String&`. The two callers that already pass
AtomString (HTMLImageElement) work without changes via implicit conversion.

* Source/WebCore/html/parser/HTMLPreloadScanner.cpp:
(WebCore::TokenPreloadScanner::StartTagScanner::processAttributes):
* Source/WebCore/html/parser/HTMLSrcsetParser.cpp:
(WebCore::bestFitSourceForImageAttributes):
* Source/WebCore/html/parser/HTMLSrcsetParser.h:
(WebCore::bestFitSourceForImageAttributes):
* Source/WebCore/loader/LinkLoader.cpp:
(WebCore::LinkLoader::preloadIfNeeded):

Canonical link: https://commits.webkit.org/311751@main

b988ea3

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	🛠 win	⏳ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	⏳ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	🧪 api-mac	✅ 🧪 api-wpe		⏳ 🛠 vision-apple
	🧪 ios-wk2-wpt	🧪 api-mac-debug	✅ 🛠 gtk3-libwebrtc
	🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 ios-safer-cpp	✅ 🧪 mac-wk2	🧪 gtk-wk2
	✅ 🛠 vision	🧪 mac-AS-debug-wk2	❌ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash cdebfce)

Details

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win	⏳ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests	⏳ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		⏳ 🛠 vision-apple
	✅ 🧪 ios-wk2-wpt	✅ 🧪 api-mac-debug	✅ 🛠 gtk3-libwebrtc
	✅ 🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 ios-safer-cpp	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
❌ 🛠 🧪 merge	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash b988ea3)

Details

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	🛠 win	⏳ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	⏳ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	🧪 api-mac	✅ 🧪 api-wpe		⏳ 🛠 vision-apple
	🧪 ios-wk2-wpt	🧪 api-mac-debug	✅ 🛠 gtk3-libwebrtc
	🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 ios-safer-cpp	✅ 🧪 mac-wk2	🧪 gtk-wk2
	✅ 🛠 vision	🧪 mac-AS-debug-wk2	❌ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🧪 vision-wk2	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 311751@main (3e936c5): https://commits.webkit.org/311751@main

Reviewed commits have been landed. Closing PR #63208 and removing active labels.